Alloy 20
UNS N08020/ W.Nr. 2.4660
“ISO 9001-2008 Certified
ISO Registered Since 1993”
Alloy 20 is an iron-base, austenitic alloy with excellent
corrosion resistance to a number of different
media and proves to be useful in a number of
applications such as flue-gas desulfurization, chemical
processing, food processing and storage as well
as pharmaceutical applications to name a few.
Application of the alloy could result in real cost savings
when carefully compared to higher-cost alloys to
determine if the necessary resistance is obtained
in the chosen media. Applications are limited to a
maximum temperature of 1000°F per ASME.
Chemical Composition
Fe ........................................................... Balance
Ni..............................................32.00% to 38.00%
Cr .............................................19.00% to 21.00%
Mo ...............................................2.00% to 3.00%
Cu ................................................3.00% to 4.00%
Cb + Ta .................................. (8 x C%) to 1.00%
Mn.............................................2.00% Maximum
Si................................................1.00% Maximum
P ..............................................0.045% Maximum
S ..............................................0.035% Maximum
C ...............................................0.07% Maximum
Resistance to Corrosion
Resistance to sulfuric acid is particularly exceptional
but the alloy shows useful resistance in phosphoric
acid, nitric acid as well as in chloride
environments. Alloy 20 is an excellent option
when chloride stress corrosion cracking is an
issue and resists pitting and crevice corrosion.
Fabrication and Heat Treatment
Alloy 20 can be formed by either hot-working or
cold-work using traditional methods. Hot forged
material should be heated between 2100°F and
2250°F with careful temperature control insuring that
the material not fall below 1800°F prior to forging.
After hot working, anneal the material by heating to
1725°F and 1850°F for a minimum of 30 minutes per
inch of thickness followed by water quench.
When stress relieving is desired, heat to a
temperature below 1000°F followed by water
quench after the desired time at temperature
has been established. Annealing Alloy 20 should
be between 1725°F and 1850°F for 30 minutes at
temperature per inch of thickness. A lower hardness
can be obtained by heating to 2100°F but his may
have a negative effect on the stabilization of the
alloy.
Welding Alloy 20 is commonly performed via, TIG,
MIG as well as submerged arc welding (SAW) using
either the matching filler metal, ER320LR for TIG and
MIG and E320LR for SAW. When welding to dissimilar
alloys such as 316 or higher alloys such as C276 and
Alloy 22, AWS ERNiCrMo-3 can be used for TIG and
MIG while using ENiCrMo-3 for SAW.
Physical Properties
Density @ Room Temp.
Poisson’s Ratio
Modulus of Elasticity (Tension)
Modulus of Rigidity
Specific Heat (32/212°F)
Electrical Resistivity (RT)
Magnetic Permeability (Annealed)
0.292 lb/in.3
0.31
28.0 X 103 ksi
11.0 X 103 ksi
0.12 Btu/lb•°F
651 ohm-cir mil/ft
1.002 @ 200Oe
Coefficient of Thermal Expansion
77°F to 212°F
77°F to 302°F
77°F to 392°F
77°F to 662°F
77°F to 842°F
77°F to 932°F
77°F to 1652°F
8.16 x 10-6 in./in.•°F
8.27 x 10-6 in./in.•°F
8.37 x 10-6 in./in.•°F
8.71 x 10-6 in./in.•°F
8.84 x 10-6 in./in.•°F
8.91 x 10-6 in./in.•°F
9.53 x 10-6 in./in.•°F
Thermal Conductivity @ 68°F
@ 122°F
@ 212°F
@ 392°F
@ 572°F
@ 752°F
84.6 Btu•in./ft2•h•°F
90.8 Btu•in./ft2•h•°F
103.0 Btu•in./ft2•h•°F
114.0 Btu•in./ft2•h•°F
126.0 Btu•in./ft2•h•°F
CM027-07, Rev. 4
Mechanical Properties1
Annealed Material
Product
Tensile
Form
Minimum
Yield Minimum Elongation Reduction of Area
(0.2% offset)
Minimum
Minimum
35 ksi
35 ksi
30%
30%
50%
-
Bar (hot or cold finished) 80 ksi
Sheet/Plate2
80 ksi
1. According to applicable ASTM specifications. 2. Maximum allowable hardness, 217 Brinell (95 Rockwell B scale).
Aqueous Corrosion Data1
Media
10% H2SO4
20% H2SO4
40% H2SO4
70% H2SO4 @ 167°F
90% H2SO4 @ 140°F
90% H2SO4 @ 185°F
90% H2SO4 @ 203°F
10% H3NO3S
1% HCl
20% C2H4O2
45% CH2O2
10% C2H2O4
50% NaOH
10% NaHSO4
20% H3PO3
Common Name
Corrosion Rate (mpy)
Sulfuric Acid
Sulfuric Acid
Sulfuric Acid
Sulfuric Acid
Sulfuric Acid
Sulfuric Acid
Sulfuric Acid
Sulfamic Acid
Hydrochloric Acid
Acetic Acid
Formic Acid
Oxalic Acid
Sodium Hydroxide
Sodium Bisulfate
Phosphoric Acid
13.2
8.4
6.0
5
4
15
27
9.6
39.6
0.0
8.4
31.2
7.2
7.2
0.2
1. All solutions at boiling during testing unless specified.
Applicable Specifications
Alloy 20 - Form
Bar
Sheet & Plate
Seamless Pipe & Tube
Welded Pipe
Welded Tube
ASTM
B473
B463
B729
B464, B4741
B468
ASME
SB473
SB463
SB464
SB468
European Standard
EN 10204-3.1
EN 10204-3.1
EN 10204-3.1
EN 10204-3.1
EN 10204-3.1
1. Electric fusion welded pipe material only.
Please contact Corrosion Materials for a complete list of available items from inventory.
In-house machine and weld facilities help insure that the
most common items will be in stock. Items not in stock
can be fabricated in a short period of time either in-house
or through our extensive, approved subcontractor and
supplier network.
We also supply a complete range of items in the following
alloys; Alloy C276, B2, B-3®, F-255, Alloy 22, 625, 200/201, Alloy
400, 405 and 600. Bar products are also available in K500,
Alloy 800H/HT®, and Alloy 6B as well as various Ti grades.
(800HT® is a registered trademark of Special Metals Corporation. B-3® is a registered trademark of
Haynes International Inc.}
The data and information contained in this pamphlet have been taken from open literature and is believed to be reliable. The information contained is
intended to be used as a guide. Corrosion Materials does not make any warranty or assume any legal liability for its accuracy, completeness or usefulness.
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CM027-07, Rev. 4